63990721 has 2 divisors, whose sum is σ = 63990722. Its totient is φ = 63990720.

The previous prime is 63990713. The next prime is 63990757. The reversal of 63990721 is 12709936.

63990721 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 50922496 + 13068225 = 7136^2 + 3615^2 .

It is a cyclic number.

It is not a de Polignac number, because 63990721 - 2³ = 63990713 is a prime.

It is equal to p_3784555 and since 63990721 and 3784555 have the same sum of digits, it is a Honaker prime.

It is not a weakly prime, because it can be changed into another prime (63990701) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 31995360 + 31995361.

It is an arithmetic number, because the mean of its divisors is an integer number (31995361).

Almost surely, 2^63990721 is an apocalyptic number.

It is an amenable number.

63990721 is a deficient number, since it is larger than the sum of its proper divisors (1).

63990721 is an equidigital number, since it uses as much as digits as its factorization.

63990721 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 20412, while the sum is 37.

The square root of 63990721 is about 7999.4200414780. The cubic root of 63990721 is about 399.9806678157.

The spelling of 63990721 in words is "sixty-three million, nine hundred ninety thousand, seven hundred twenty-one".